Thermal-History Dependence of Phase Separation Induced by Radical Polymerization of 2-Chlorostyrene in the Presence of Polystyrene

Abstract

Thermal-history dependence of phase separation induced by radical polymerization of 2-chlorostyrene in the presence of polystyrene was studied by making a stepwise temperature change (jump) to a higher temperature T2 during the phase separation. Morphological structure of poly(2-chlorostyrene)-rich domains changed from droplets to continuous domains after the temperature change if the duration at the first phase-separation temperature T1 was longer than a certain value t1*. The morphological change to the continuous domains was accompanied by an increase of the volume of poly(2-chlorostyrene)-rich phase. The increase of the volume was observed even when temperature was jumped after the polymerization reaction finished. The minimum duration t1* at T1 required for the morphological change to occur after the temperature jump increased with T1 but scarcely depended on T2. An explanation for the experimental results was proposed on the basis of the difference in the viscosity dependence between the phase-separation rate and the reaction rate.